1. Field of the Invention
The present invention relates to a process of effectively recovering copper having a high purity as a copper resource from a copper wire having an enamel coating thereon and a so-called enameled copper wire, in particular in a wound form and in the form of a so-called "winding."
2. Description of the Related Art
A motor has been often used as a driving means for domestic appliances and industrial machineries. Recently, environmental protection and resource exhaustion are very interested socially, and technical development related to effective use and recycle of resources has to be rapidly accelerated, in which the motor is also considered.
An arrangement of a motor is schematically shown in a cross-sectional view in FIG. 1 which is used in the domestic appliances or the industrial machineries. As shown in FIG. 1, the motor comprises a stator 1, a rotor 2, a shaft 3 of the rotor 2, a bearing 4, an end bracket 5 as a motor shell, and a frame 6. The stator 1 has winding 8 formed by winding an enameled copper wire 7 around a core 10 with a predetermined electrical specification, and the wire 7 has an enamel coating outside which functions as an insulation. Passing an electric current through the winding from the outside generates an electromagnetic force, which rotates the rotor 2.
The stator 1 is often subjected to a varnish treatment for the purpose of insulation reinforcement and mechanical reinforcement of the winding 8. In addition, a so-called molded motor is often used in which a stator 1 is embedded in a resin body 9 as shown in FIG. 2. Such a motor is used as a fan motor for the purpose of small sizing, suppressing noise and improving reliability in for example a room air conditioner. Further, a commutator motor is used in a vacuum cleaner as a driving means. In the commutator motor, a rotor (or an armature) having a commutator also has winding which has been varnish- treated.
With respect to the above motors, disassembling and separation of the winding 8 from the core 10 is not so easy since the winding 8 composed of the enameled copper wire 7 has been bonded together or embedded in the resin mold 9. Thus, it is difficult to economically recover metals as resources from motors collected as wastes. Therefore, there is no other way rather than to dispose the collected spent motors as metal scraps including contaminants or to bury them as they are as industrial wastes. The winding which is particularly used for the motors is worth re-using since it is made of electrolytic copper of which purity is very high (such as not less than 99.9% by weight) so as to reduce copper losses and improve motor efficiency.
There is a process of separating at least metallic elements of electromagnetic members such as winding, a core, and so on from a resin mold by dipping a rotor including the resin mold in an alkali solution so as to alkaline-decompose the resin mold (see Japanese Patent Kokai Publication No. 8-340661). In this process, the resin mold for the electromagnetic members is merely broken by the alkali decomposition so that metal elements are collected. The process may leave the resin on the metal elements and finally there is no other way to treat the collected metal elements as low quality metal scraps.